Method and apparatus for measuring area

ABSTRACT

To nondestructively measure the area of a relatively flat object, a length increment encoder controls the signals generated by a width sensing array as a scanning section containing the width sensing array is moved relative to a fixed reference over the object to be measured in a manner dependent on increments of length moved by the scanner and independent of the velocity of the scanner so that the signals from the width sensing array are integrated with respect to length, with the signals being accumulated in a counter to represent the area of the object. In one embodiment, an optical system provides an image of a line of width on the object being scanned, which image is reduced and projected onto a sensing array to improve the resolution of the area measuring instrument and to reduce its bulk.

United States Patent 1191 [111 3,782,833 Biggs et al. 1 Jan. 1, 1974[54] METHOD AND APPARATUS FOR 3,717,414- 2/1973 Hall et al 250 219 WDMEASURING AREA 3,698,818 10/1972 Bowker et al 3,515,487 6/1970 Hatcher,Jr. et al 356/157 [75] lnventors: William W. Biggs; Max D. Clegg,

both of Lincoln, Nebr- Primary Examiner-John K. Corbin [73] Assignee:Lambda Instruments Co., Lincoln, Ass'stam f McGraw Attorney-Vmcent L.Carney Nebr.

[22] Filed: May 25, 1972 [57] ABSTRACT [21] Appl. No.: 256,921 Tonondestructively measure the area of a relatively flat object, a lengthincrement encoder controls thesignals generated by a width sensing arrayas a scan- [52] 356/158 250/219 250/ ning section containing the widthsensing array is 51 I t Cl Golb g moved relative to a fixed referenceover the object to i 158 159 be measured in a manner dependent onincrements of I l 0 care 0 2i 9 b 2 length moved by the scanner andindependent of the velocity of the scanner so that the signals from thewidth sensing array are integrated with respect to [56] Referenceslength, with the signals being accumulated in a UNITED STATES PATENTScounter to represent the area of the object. In one em- 2,910,90811/1959 Meyer, Jr 356/158 bodiment, an optical system provides an imageof a 3,513,444 5/ Henderson 6t 356/157 line of width on the object beingscanned, which Metcalf .1" image is reduced and projected onto a ensingarray to gf improve the resolution of the area measuring instruag ey e ar 2,719,236 9/1955 Soltis 356/157 ment and to reduce bulk 3,222,97912/1965 Webster 250/219 WD 16 Claims, 6 Drawing Figures El El El El ElE1 COUNTER AND CONTROL CIRCUITRY PATENTEDJAH 11914 sum 1 or 2 El El E][I U U COUNTER AND CONTROL CIRCUITRY CONTROL UNIT FOR SCANNER FLYINGSPOT SCANNER).

I PHTfiBFLL 25 'PATENTED H974 3.782.833

' sum 2 or 2 24 FIG 4 l im 4 2 I 37 4 IN CEQ EEA QK I I ENCODER Fig-El II PHOTCDIODE ARRAY l *1 1 v I86 |8D SHIFT REGISTER L H A4 r--- n I 64 60M30 |8A 188 GATE I 59 1 I 'CONTROL U [:1 EDGE] I UNIT I READ-OUT COUNTERI METHOD AND APPARATUS FOR MEASURING AREA This invention relates tomethods and apparatuses for measuring the area of flat objects and moreparticularly relates to apparatus and methods for measuring the area offlat objects without having to detach the objects from a larger object.

One type of automatic area measuring apparatus measures the length of aflat object such as a leaf and measures the width of the object atdifferent points along its length, using these measurements to form anintegral of the width with respect to the length thus obtaining the areaof the flat object. In measuring the width and length of the flatobject, electric pulses are generated which are proportional in numberto the area and these pulses are accumulated to provide a total countrepresenting the area of the flat object.

in one class of prior art automatic area measuring apparatuses of thistype, the object to be measured is detached from any portion that is notto be measured. For example if the area of a leaf is to be measured itis pulled free from the stalk and placed on a conveyor. The conveyormoves the object to be measured past a width scanner that scans acrossthe object with a flying spot scanner, generating signals as it scans,while the object is moved at a constant rate by the conveyor so that thesignals obtained by scanning the width may be considered as beingintegrated with respect to time to provide an area measurement for theobject. The flying spot is obtained by focusing light from anincandescent lamp into a spot and moving the spot.

The prior art apparatus of this class have several disadvantages suchas: (1) they are excessively large and not portable; and (2) they arenot suitable for nondestructive measurements.

Firstly, the prior art apparatuses are excessively large because themotors and conveyor system are heavy and occupy a great deal of space.Moreover, the motors and incandescent lamps require considerable powerand therefore require bulky sources for the power. The incandescent lamprequires substantial power because it is on continuously and thereforecontinuously consumes power. Moreover, the flying spot scanner is bulkybecause it must scan across a large area.

Secondly, the apparatus is not suitable for nondestructive testingbecause the object to be measured must be moved along a conveyor systemthrough the width measuring apparatus. This requires that it be detachedfrom all other large or stationary objects. For example, a leaf must bepulled free from its stalk or a map having a certain area to beintegrated must be cut to separate the area to be measured from the mapso that it may be run through the conveyor system for measurement.

Accordingly, it is an object of this invention to provide a novel methodand apparatus for measuring area. It is a further object of thisinvention to provide a nondestructive measuring method and apparatus formeasuring the area of objects.

It is a still further object of the invention to provide a method andapparatus especially suitable for making measurements relating to plantlife.

It is a still further object of the invention to provide an areameasuring apparatus and method in which a scanning device is moved withrespect to a stationary object to measure its area.

It is a still further object of this invention to provide an areameasuring apparatus and method in which the length and width of anobject are measured with one of the length and width being integratedwith respect to the other of the length and width.

it is a still further object of this invention to provide an areameasuring method and apparatus which includes an incremental lengthencoder which generates signals relating to length which are notdependent upon the velocity of motion of the object with respect to thescanner.

lt is a still further object of this invention to provide an apparatusand method for measuring an area of an object in which the lengthmeasuring device generates synchronizing signals to operate a widthmeasuring device. 1

It is a still further object of this invention to provide an areameasuring apparatus which is small and compact and therefore portable.

It is a still further object of this invention to provide anelectrically operated area measuring apparatus which does not requirelarge amounts of power.

It is a still further object of this invention to provide an areameasuring apparatus having an optical system to form a reduced sizeimage of at least one portion of an object that is being measured.

It is a still further object of this invention to provide a novel methodand apparatus for measuring the area of an object which method andapparatus provides improved resolution.

It is a still further object of the invention to provide an apparatusand method for measuring the area of an object in which the sensingenergy is intermittently applied rather than continuously applied.

In accordance with the above, and further objects of the invention, theautomatic area measuring apparatus includes a length measuring systemand a width measuring system controlled by the length measuring system.The length measuring system operates independently of the speed ofmeasuring length, generating signals relating only to the length of anobject that is scanned. The length measuring system also controls thewidth measuring system, causing the width to be measured at selectedincrements of length to represent the integral of the width with respectto the length regardless of the rate of scanning.

The length measuring system of the automatic area measuring apparatusincludes a tab at one end and a signal generator at the other end. Thewidth measuring system and the signal generator are included within amanually moved scanner that forms a part of the scanning section, withthe signal generator: (1) moving a distance within the manually movedscanner that is proportional to the distance that the manually movedscanner moves with respect to the tab during the measurement of the areaof the object; and (2) generating a signal at each increment of lengththat the manually moved scanner moves with respect to the tab.

The width measuring system includes: (1) a scanning area across whichthe object moves during scanning; (2) a light source which transmitslight across the width of the object to be measured and portions of thescanning area on each side of the object, some of which light is blockedby the object and some of which is passed around the object, and (3) anarray of photocells which detect the portion of the light that is passedaround the object to be measured.

The signals from the length measuring system control the readout fromthe width measuring system so that the signals are read from the widthmeasuring system each predetermined increment of length of the object tobe scanned that is covered by the scanner. With this mechanization thesignals read from the array of photocells represent the integral of thewidth of the object being measured with respect to its length, which isthe area of the object scanned.

The signal generator which is a part of the length measuring apparatusincludes a chopper wheel having circumferentially spaced apertures,around its periphery. A light source and a photocell are spaced fromopposite sides of the chopper wheel, aligned with the circle ofapertures and each other, so that a plurality of pulses are generated bythe photocell as the apertures rotate between the lamp and thephotocell. The chopper wheel is rotated as the cord is pulled by themotion of the scanner with respect to the tab on the end of the cord.

The width measuring apparatus includes a shift register which stores anumber of pulses equal to the number of photocells that were covered bythe object to be measured and shifts this information into anaccumulator at each of the length increments established by the lengthmeasuring system.

In one embodiment, an optical system focuses a reduced size image of theobject to be measured through a lens system onto the array. By theproper design of the optical system, a reduction in size is obtainedthat permits the selection of special commercial sensing arrays. Thearrays may be selected for economy and for good resolution so as toprovide a more compact and better-operating area measuring device. Thescanner may also use light applied to the object from the same side asthe sensing array, with the sensing array being sensitive to aparticular color so as to enable the measurement of a colored area ofthe object while scanning from one side.

In operation, the tab on one end of the cord in the length measuringsystem is held at one location on the object to be measured. Forexample, it may be held near the stalk of the leaf, the area of which isto be measured while the leaf extends through the scanner. The scanneris then pulled across the leaf while the one end of the cord is heldstationary so that the length measuring apparatus turns the signalgenerator to generate signals representing increments of length of theobject that is scanned. The signals from the length generating apparatuscause the shift register to read a number of pulses representing thewidth of the object at each increment of length into the counter. Thetotal of the pulses in the counter therefore represents the area of theobject to be scanned.

From the above description, it can be understood that the area measuringapparatus and method of this invention has several advantages such as:(1) it is able to nondestructively measure the area of objects such asleaves while they are still attached to the stalk; (2) it is light inweight and small in size so as to be portable; (3) it is able to providemeasurements of area with high resolution; (4) it is inexpensive becausethe optical system provides an image which may be adjusted to besuitable for economical sensing arrays; (5) it requires a relativelysmall amount of power because the light utilized in sensing the width ofthe object may be pulsed during the sensing operation so that it doesnot require continuous operation; (6) in one embodiment, it may scan anobject from only one side of the object, such as for example scanningrough and irregular objects that cannot be conveniently fed through thescanner (7) it has a good noise rejection characteristics because itutilizes a light source which includes very little infrared light; and(8 it includes an optical system that focuses on the object to bemeasured thus eliminating diffused light and is conveniently constructedfor the insertion of filters to remove further unwanted frequencies oflight. 7

The above noted further objects of the invention will be betterunderstood from the following detailed description when considered withreference to the accompanying drawings in which:

FIG. 1 is a simplified diagramatic view, partly in perspective andpartly as a block diagram, of an embodiment of the invention as it isutilized in one application;

FIG. 2 is a plan view of a portion of an embodiment of the invention;

FIG. 3 is a side view of a portion of an embodiment of the invention;

FIG. 4 is a block diagram of the electrical circuitry used in anembodiment of the invention; and

FIG. 5 is a simplified perspective view of another embodiment of theinvention.

FIG. 6 is a block diagram of a portion of another embodiment of theinvention. I

In FIG. 1, there is shown a leaf 16 and an automatic area measuringinstrument 10 having an incremental area measuring unit 12 and counterand control circuitry 14 with the leaf 16 being positioned within theincremental area measuring unit 12, the incremental area measuring unit12 being electrically connected to the counter and control circuitry 14through a cable 18 of electrical conductors. The incremental areameasuring unit 12 includes a scanning section 20 and a stationarysingle-dimension measuring section 22 having a shank portion 26 with atab 24 at one end adapted to be positioned in a fixed relationship withrespect to the leaf l6 and a shank portion 26 adapted to move into andout of the scanning section 20 at the other end.

To permit the area of a leaf 16 to be measured in the field withoutdetaching the leaf 16 from its stalk, the automatic area measuring unit12 is portable and easily movable to the field where it can be used tomeasure the leaf 16 while the leaf is still on its stalk by scanning theleaf with the incremental area measuring unit. The incremental areameasuring unit 12 includes suitable apparatus for generating signals,which signals are integrated to provide the area of the stalk 16 as thescanning section 20 is moved with respect to the stalk 16 while the tab24 of the stationary single-dimension measuring section 22 remainsfixed. In the preferred embodiment the area of the leaf 16 is measuredby measuring one dimension with the stationary singledimension measuringsection 22 and the other dimension by means of a second measuringapparatus within the scanning section 20 with one of the first andsecond dimensions being integrated with respect to the other dimensionby the method of rectangular approximations.

To measure the first dimension, the stationary singledimension measuringsection 22 generates pulses in proportion to the length of its shank 26as the tab 24 is held stationary at one end of the leaf l6 and thescanning unit 20 is moved in the direction of the opposite end of theleaf 16, with the second measuring apparatus within the scanning unitbeing positioned so as to at least cover the ends of the leaf l6 andmoving with its long dimension orthogonal to the shank portion of thestationary single-dimension measuring section 22.

The shank portion 26 of the stationary singledimension unit 22 may beany type of apparatus that is movable with respect to the scanning unit20. In the preferred embodiment it is a flexible member or cord which iswound on a wheel within the scanning section 20 as the scanning sectionmoves toward the tab 24 and unwound as the scanning section 20 movesaway from tab 24. However, it may be a rigid member passing through thescanning section 20 which generates signals by any other method as aportion of it moves with respect to the scanning section 20. Moreover,it is not necessary for the entire stationary single-dimension measuringsection 22 to move with respect to the scanning section 20 but only aportion of it may be moved to generate signals which are related to thedistance the scanning section 20 moves with respect to the leaf 16. Forexample, a wheel-may be mounted within the scanning section 20 so thatthe center of rotation of the wheel is stationary in position within thescanning section 20 but the periphery of the wheel moves with respect tothe scanning section 20 to generate the necessary signals.

To measure the second dimension of the leaf 16 as the scanning section20 is moved with respect to tab 24, the scanning section 20 includes anelongated sensing array 34 positioned with its longitudinal axisorthogonal to the direction of motion of the scanning section 20 withrespect to the tab 24 as the scanning section 20 is moved away from thetab 24 and the stalk of the leaf 16. The elongated sensing array 34measures the second dimension of the leaf 16 at locations determined bythe single-dimension measuring unit 22 as the scanning section 20 movesfrom the tab 24 which dimension is automatically multiplied by theincrement of length at each location to provide an incremental unit ofarea of the leaf 16, which incremental area is the product of thedistance that the scanning section 20 has moved in a short period oftime times the second dimension.

In the preferred embodiment the single-dimension measuring section 22generates a signal which represents one unit of length each time thatthe incremental area signal is to be provided so that the incrementalarea signal represents one increment length multiplied by the number ofunits provided by the elongated sens ing array. With this mechanizationno multiplication is necessary since the product always is one times thenumber generated by the elongated sensing array. However, severalincrements could be measured each time that the incremental area signalis generated in which case a multiplying operation would be appropriateto calculate the incremental area.

In the preferred embodiment, the scanning section 20 includes a baseportion 28 and a cover 30. The cover 30 includes within it a source oflight such as an array of light emitting diodes, the power for which issupplied through the electrical cable 18 through a conductor separatefrom the conductor that applies signals to the counter and controlcircuit 14. The cover 30 is hinged to the base 28 at 32 so that the leaf16 may be positioned between the base 28 and the cover 30 with lightfrom the light emitting diodes impinging against the leaf 16 and the topsurface of the base 28 where the leaf does not cover the base. The base28 includes the elongated sensing array 34 which in the embodiment ofFIG. 1 is a single line of photocells which generate different signalsdepending on whether the leaf I6 covers them or does not cover them asthe scanning section 20 moves with respect to the tab 24.

While the elongated sensing array 34 is a single line of photocells theembodiment of FIG. 1, other arrangements may be used to generate signalsrepresenting the width of the leaf 16 across each incremental area thatis to be formed by the product of the signal from the stationarysingle-dimension measuring section 22 and the elongated sensing array34. For example, an imaging system may be positioned within the base 28to project an image of the width of the leaf upon a smaller sensingarray mounted within the base 28. Moreover a flying spot scanner 23(FIG. 6) cooperating with a single photocell 25 may be substituted forthe array of photodiodes and elongated beam of light used in thepreferred embodiment. Of course other width measuring devices may beused such as pressure or moisture sensing devices or the like.

While in FIG. 1 the automatic area measuring unit 10 is shown measuringa leaf 16, it may be used to measure any other type of relatively flatobject to be determined the area thereof. While virtually any type ofrelatively flat object can be measured with the automatic area measuringinstrument 10, the automatic area measuring instrument 10 has particularutility in measuring objects which should not be moved or removed from alarger object. For example, documents are frequently bound to largevolumes and such documents may contain areas that can be measured toindicate certain statistical information such as elevations, rainfalland the like information on maps. The automatic area measuringinstrument 10 may be used to measure the areas on a single page of thebound volume without removing the page from the volume. However, undersome circumstances, relatively minor modifications are necessary in thescanning section 20 to adapt it for sensing the particular portions ofthe document. For example, it may be desirable to use a sensing mediumother than light on some documents or a light source positioned withinthe base 28 to reflect light from a page upon a light sensing array,with an appropriate filtering equipment being within the base 28 tocause the sensing array to be responsive only to a particular reflectedcolor- To accumulate the signals representing incremental areas of theleaf 16 and to provide the necessary control functions for theincremental area measuring unit 12, the counter and control circuitry 14includes a counter that accumulates the signals from each incrementalarea measurement and provides a total representing the area of the leafscanned by the scanning section 20 and a control circuit for reading theincremental area measurements from the scanning section 20 to thecounter and control circuit 14 at the end of each increment of length.

In the operation of the automatic area measuring instrument 10, theentire automatic area measuring instrument 10 is generally brought tothe location of the object to be measured. For example, it may becarried to a library having volumes, the pages of which are to bescanned so that certain portions of the pages may be measured, orcarried to certain plants in a field, the leaves of which are to bemeasured.

An important use of the automatic area measuring instrument 10 is in thefield of plant science. In certain experiments in the field of plantscience, it is desireable to measure the area of leaves of plantswithout removing the leaves from the plants. The automatic areameasuring apparatus 10 is especially useful in this application sincethe scanning section may be moved with respect to the leaf to measureits area without removing the leaf. Of course, it is also useful inother types of nondestructive testing that are analogous to this use inplant science.

When the automatic area measuring instrument It) has been brought to thelocation where an object such as a leaf 16 is to be measured, theincremental area measuring unit 12 is positioned with the leaf 16between the base 28 and the cover 30 while the counter and controlcircuitry 14 rests nearby such as on the ground, being electricallyconnected to the incremental measuring unit 12 by the cable 18. With theleaf l6 positioned between the base 28 and the cover 30, the tab 24 ofthe stationary single-dimension measuring section 22 is held near thestalk at the base of the leaf 16 with the scanning section 20 beingpositioned adjacent to it so that its trailing edge touches the tab 24.

While the tab 24 is held stationary with respect to the leaf 16, thescanning unit 20 is moved along the leaf, moving in the same directionas the shank 26 of the stationary single-dimension measuring section 22,with the array 34 being parallel to a leading edge of the scanningsection 20 and moving in a direction orthoginal to the shank 26 of thestationary single-dimension measuring section 22. While the scanningsection is moving, the leaf 16 is held between the cover 30 and the base28 by a stop which is positioned between the base 28 and the cover 30 atthe end opposite to the hinge 32.

While in the preferred embodiment, an accurate measurement is onlyobtained if the scanning section 20 is moved in such a way that thearray 34 is always orthogonal to the shank 26 of the stationarysingledimension measuring section 22, it is obvious that otherarrangements may be made in which the shank 26 is moved at an angle tothe array. Such arrangements may be incorporate in a computer thatadjusts for changes in the angle between the shank 26 and the array 34or arrangements in which the corrective measurement is obtained onlywhen some constant angle other than 90 is maintained.

As the scanning section 20 moves with respect to the tab 24, the shank26 moves with respect to a portion of the cover 30. The motion of theshank 26 with respect to the cover 30 generates pulses proportional tothe distance moved. In other words, a single pulse is generated withinthe cover 30 for each increment of distance moved by the scanningsection 20 with respect to the tab 24.

As the scanning section 20 is being moved with respect to the tab 24,the elongated measuring array 34 generates signals proportional to thelength of the leaf 16 in a direction orthogonal to the shank 26 of thestationary single-dimension measuring section 22. Each time that thescanning section 20 moves one increment of length to cause thestationary single-dimension measuring section 22 to generate one pulse,the longitudinal measuring array 34 generates a signal indicating thedimension of the leaf 16 in a direction orthogonal to the shank 26. Atthis time, the control unit in the counter and control circuitry 14causes this signal to be read into the counter for accumulation. Ofcourse, the units of distance that correspond to a signal in bothdirections of measurement are dimensionally correct for the applicationof the automatic area measuring instrument.

The counter within the counter and control circuitry 14 stores anaccumulated total of all of the incremental areas scanned by thescanning section 20. Accordingly when the scanning section 20 has beenpulled the full length of the leaf 16, the counter within the counterand control circuitry 14 has recorded a number representing the totalarea of the leaf 16.

Of course, any portion of the leaf 16 may be measured rather than theentire leaf by holding the tab 24 at a selected position and moving thescanning section 20 over the portion of the leaf that is to be measured.Moreover, the total area of several leaves may be measured and thistotal area accumulated within the counter of the counter and controlcircuitry 14 by measuring the area of each leaf separately whilepermitting the accumulated total from previous measurements to remain inthe counter.

In FIG. 2, there is shown a signal generating apparatus 36 which is aportion of the stationary singledimension measuring section 22. Thesignal generating apparatus 36 includes a chopper wheel 38 having acenter of rotation 40 about which a flat disc 42 rotates. A plurality oflight apertures 44 are spaced around the outer periphery of the of thedisc 42 forming a closed circle, with a photocell 46 being mounted onone side of the disc 42 and a source of light 48 being mounted on theopposite side in line with the circle so that as the apertures 44 arerotated about the center of rotation 40, the light from the source oflight 48. shines through one aperture at a time onto the photocell 46 tocause the photocell to generate a pulse each time that the chopper wheelrotates through the angle between two successive apertures. The shank 26is wound around a reduced diameter pulley section 50 of the chopperwheel 38 so that, as the shank portion 26 moves with respect to thecenter of rotation 40 within the scanning section 20, the chopper wheel38 is rotated so that the photocell 46 emits one pulse for eachincrement of motion of the scanning section 20 with respect to the tab24 (FIG. 1).

In FIG. 3 there is shown an elevational fragmentary view of a portion ofa stationary single-dimension measuring unit 22 including the shankportion 26, the chopper wheel 38, and the take-up reel 52. The shankportion 26 is wound into the takeup reel 52 which is biased to retractit as the scanning section 20 moves toward the tab 24.

As best shown in FIG. 3, the shank 26 is wound around the reduceddiameter pulley section 50 so that as the shank portion 26 moves withrespect to the scanning section 20, the chopper wheel 38 is rotated tomove successive ones of the apertures 44 between the source of light 48and the photocell 46 (FIG. 2). The ratio of the radius 54 of the pulleysection 50 to the radius 56 of the circle 58 passing through theapertures 44 determines the ratio between the velocity of the scanningsection 20 to the tangential velocity of the apertures 44 as they passbetween the source of light 48 and the photocell 46. By selecting thisratio and the number of apertures within the circle 58, the number ofpulses that are generated by the photocell 46 for each unit length ofmotion of the scanner with respect to the tab 24 is controlled. Thisnumber of pulses may be selected to correspond to the units ofmeasurement desired and to the precision desired in measuring the area.The spacing between the photocells of the longitudinal measuring array36 (FIG. 1) is also adjustable to control the selection of the properdimensions and the resolution of the area measurements.

In FIG. 4 there is shown a block diagram of the electronic systemincorporated in the incremental area measuring unit 12 and in thecounter and control circuitry 14, with the incremental area measuringunit 12 and the counter and control circuitry 14 being electricallyconnected by the conductors l8A-18D within the cable 18 (FIG. 1). Theincremental area measuring unit 12 includes the stationarysingle-dimension measuring section 22 and the scanning section 20.

To generate signals representing the increments of length scanned'by thescanning section 20, the singledimension measuring section 22 includesthe cord 26 with the tab 24 on one end and a length increment encoder 37on the other end. The length increment encoder includes the signalgenerator 36 shown in FIG. 3 and is located within the scanning section20. The scanning section 20 includes the photodiode array 34, a shiftregister 55 and a reset switch 57, with the photodiodes in the diodearray 34 each being electrically connected to a different stage of theshift register 55.

The control and counter circuitry 14 includes a control unit 59, an ANDgate 60 and a read-out counter 62, with the AND gate 60 having one ofits two inputs electrically connected to one output of the control unit59 through a conductor 64 and the other of its inputs electricallyconnected to the shift register 55, the output of the AND gate 60 beingconnected to the readout counter 62.

To read pulses generated by the photodiode array 34 from the shiftregister 55 representing the width of the object at an increment oflength, the control unit is connected to the length increment encoder 37through a conductor 18A to receive pulses indicating the increments oflength and connected to the shift register through a conductor 188 toprovide signals to the shift register 55 reading the pulses from theshift register through the gate 60 which is opened at this time and intothe read-out counter 62. The pulses are read from the shift counter tothe AND gate 60 through conductor 18C by pulses from a multivibratorwithin the control unit 58 which pulses are applied to the shift counter54 through the conductor 188. These pulses are read through the AND gate60 through the conductor 64 into the readout counter 62. The resetswitch 57 is connected to the read-out counter 62 through the conductor18D to control the reseting of the counter so as to control the portionsof an object or the number of objects that are to have their areaaccumulated in the read-out counter 62.

In the operation of the circuitry shown in FIGS. 2, 3 and 4, single linemeasurements of width represented by a number of pulses from readout of-a line of photocells are controlled by the incremental distance as thescanner 20 moves across the length of the object to be measured. Forthis purpose, the length increment encoder 37 includes the chopper wheel38 which generates pulses in proportion to the length that the scanneris moved with respect to the leaf 16. These pulses are applied to thecontrol unit 59 through the conductor 18A as the scanner 20 is movedalong the length of the leaf 16. In response to the pulses from thelength increment enc'oder, a control unit 59 causes a number of pulsesto be read to the readout counter that is proportional to a line acrossthe width of the leaf 16.

In the preferred embodiment the pulses representing the width aregenerated by a photodiode array extending across the scanning area ofthe scanning section. However, it is possible to utilize a singlephotocell and a flying spot scanner rather than an array of photocells.To accomplish this, the flying spot scanner scans across the width ofthe leaf, and while it scans across the leaf, a sensor causes a numberof clock pulses to be generated representing the width of the leaf. Whenusing a flying spot scanner the width of the leaf is multiplied by asingle increment of length.

The pulses generated by the length increment encoder 37 are applied tothe control unit 59 which generates a square wave pulse and applies itto the AND gate 60 through the conductor 64. This pulse occurs betweenpulses generated by the length increment encoder 37 as the aperturesrotate between the source of light 48 and the photocell 46. Each pulseapplied to the conductor 64 therefore represents one increment ofdistance between tab 24 and scanner 20.

While the AND gate 60 is held open by a pulse applied to the conductor64, the control unit 59 applies a sufficient number of pulses, (which inthe preferred embodiment is 128) to the conductor 188 to read-out theshift counter 54 through the conductor 18C and to open AND gate 60 so asto pass pulses to the read-out counter 62. The shift register 55 storespulses generated by photodiodes in the photodiode array of 34 which donot receive light. Accordingly, the number of pulses read from the shiftcounter 54 is proportional to the width of the leaf or other objectbeing scanned.

When an area increment is completed, whether it is for a portion of aleaf, a full leaf, or several leaves, a reading is taken from theread-out counter 62 and the reset button 56 is depressed to reset theentire circuit.

In FIG. 5, there is shown another embodiment 66 of scanning sectionusable with the incremental area measuring device 10. In the embodimentof scanning sec tion 66, an optical system is utilized to form a reducedsize image of the width to be measured, thereby permitting a reductionin the size of the scanner so as to render it more portable and easierto use. When an array of sensing units is utilized as in the preferredembodiment of this invention, small components may be in the array toperform the scanning operation and when a flying spot scanner is usedwith a single sensing device, the flying spot scanner may be smallerbecause the distance of the scan is less when this optial system isused. Under both of these circumstances the scanning section itself isreduced in size, and under some circumstances, reduced in cost.

In FIG. 5, the scanning section 66 is shown with the cover 68 positionedon the bottom and the base broken away to expose the optical system 70and the array of photodiodes 72. A light source 74 is positioned in thecover to transmit light to the leaf 16, which light source, in thepreferred embodiment, includes a plurality of light emitting diodes(LED), which are gallium arsenide phosphide diodes. These diodes emitlight predominately of a red frequency, which light is absorbed readilyby leaves. By using an LED light source, only relatively low power isnecessary and to obtain adequate contrast between the leaf and thebackground thus reducing the size and weight of the scanner 66.

In the preferred embodiment, the amount of power required is furtherreduced by pulsing the LED light source when the array 72 is to be read.This enables the LED source to be off at other times thus conservingpower. Other types of light sources such as incandescent lamps can beused, but since they normally operate continuously, more power isrequired for the continuous operation thus requiring a heavier areameasuring instrument. Moreover, other types of lamps such asincandescent lamps transmit frequencies of light which are transmittedreadily by leaves and are difficult to filter from the apparatus.Accordingly, the contrast of the system is better when an LED lightsource is used than when an incandescent light source is used.

A further advantage of the optical system 70 is that it may be focuseddirectly on the leaf 16. Because the optical system is focused on theleaf 16, diffused light is not transmitted as readily through theoptical system to the array 72 thus increasing the contrast and noiserejection of the system.

The optical system 70 includes: (1) a slit 76 extending longitudinallyacross the width of the leaf 16 to pass light on opposite sides of theleaf across its width and to block diffused light; (2) a first mirror 78above and and above the slot 76 and at an 45 angle with the top surfaceof the leaf 16 so as to form an upright image behind the mirror 78; (3)a second mirror 80 which is orthoginal to the top surface containing theslit 76 and at an angle with the first mirror 78; and (4) a lens system82 having its longitudinal axis in line with the sensing array 72 and atan angle with the second mirror 80. The first mirror 78 and the secondmirror 80 are first surfaced mirrors so as to avoid errors caused byrefraction.

The first image of the line across the width 16 that passes through theline slit 76 is formed behind the mirror 78 the same distance as thesurface of the mirror 78 is above the top surface of the leaf 16. Thesecond image is formed behind the second mirror 80 a distance which isproportional to the angle between the second mirror 80 and the firstmirror 78 so that by increasing the angle between the first and secondmirrors the image may be projected further behind the second mirror 80.This angle is adjusted until the image is a sufficient distance behindthe second mirror 80 so that ratio of the object distance to the lensimage distance is the desired reduction factor. In the preferredembodiment this reduction factor is 20 to 1 so that a 5 inch wide leafis reduced to an image of one quarter inch. This angle is also selectedso that the position of the lens system 82 in focusing upon the secondimage is not an excessive angle to decrease the bulk of the scanner 66.

Although a specific mirror system is shown in FIG. 5, it it obvious thatother types of optical systems may be used for the same purpose, thegeneral purpose being to reduce the size of the image and to position itin such a way as to make the scanning section less bulky.

In the operation of the scanning section 66, the tab 24 is positioned atthe base of the leaf l6 and adjacent to the side of the scanning section66. With the tab 24 held stationary, the scanning section 66 is pulledover the leaf 16 so that the tab 24 moves relative to the scanningsection 66 as the scanning section 66 moves over the leaf 16. Within thescanning section 66, the leaf I6 is held at a fixed location by apressure flap so as to maintain its optical distance from the lenssystem constant, thus avoiding errors due to changes in the imagereduction ratio.

As the scanning section 66 moves over the leaf 16, light from the LEDlight source 74 shines through the slit 76 wherever it is not covered bythe leaf 16. This forms a moving line image the width of the leaf 16 asthe scanner 76 moves away from the tab 24.

The moving line image is projected behind the fist mirror 78 by the samedistance that the surface of the mirror is away from the top surface ofthe leaf 16. This image is received by the mirror 80 and projectedbehind this mirror by a sufficient distance to provide the proper imagereduction on the array 72 after passing through the lens system 82 whichis focused on the image. This image reduction in the preferredembodiment is 20 to I so that a 5 inch wide leaf is reduced to onequarter of an inch on the sensing array 72.

While in the preferred embodiment the reduction ratio of 20 to l isprovided, it is to be understood that other reduction ratios are easilyobtained by adjusting the arrangement of mirrors and lens. Because thereduction ratio is adjustable, the array 72 may be selected from a widevariety of different commercial arrays of different sizes. Because ofthis adaptabilty, optimum size arrays have been selected which reducethe bulk of the scanner 66. The reduction in size also improves theresolution by enabling the use of integrated circuit packages having alarger number of photocells for the same size leaf that is to bescanned.

Moreover, because the lens 82 has a relatively small entrance aperture,it is relatively easy to mount filters in front of it when desired. Forexample, under some circumstances, filters may be used to filter outinfrared light.

Although a preferred embodiment has been described in someparticularity, it is to be understood that many variations are possiblein the preferred embodiment without deviating from the invention.Therefore, it is to be understood that, within the scope of the appendedclaims, the invention may be practiced otherwise than as specificallydescribed.

What is claimed is:

l. A method of measuring the area of a substantially stationary objectwith a portable instrument having at least first and second portionsmovable with respect to each other without moving the object to a newlocation comprising the steps of:

bringing the portable measuring instrument to the location where thestationary object to be measured is located;

establishing a reference location with respect to the object by placingat least one part of said first portion of the measuring instrument at aposition that is stationary with respect to the object;

moving at least one part of the second portion with respect to theobject while the part of the first portion is stationary with respect tothe object and said object remains substantially stationary;

sensing the distance the part of the second portion moves with respectto the part of the first portion and a dimension of the object that istransverse to the direction of motion of the part of the second portion;

generating at least a first signal related to the distance moved by thepart of the second portion and the dimension transverse to the directionmoved; and

obtaining a second signal representing the area of said object from saidfirst signal.

2. A method according to claim 1 in which:

the step of generating said first signal includes the steps ofgenerating a third signal which is independent of the rate of motion ofsaid part of said second portion with respect to said part of said firstportion and dependent on the distance said part of said second portionmoves with respect to said part of said first portion, and generating afourth signal representing said dimension transverse to the directionmoved; and

the step of obtaining said second signal includes the step of obtainingsaid second signal from said third and fourth signals.

3. A method according to claim 2 in which the step of obtaining saidsecond signal representing the area of said object includes the step ofperiodically multiplying increments of said third signal by said fourthsignal to obtain the integral of one of said third and fourth signalswith respect to the other of said third and fourth signals.

4. A method according to claim 2 in which:

said step of generating a third signal which is independent of the rateof scanning includes the step of generating a plurality of differentfirst-dimension increment signals each representing one increment ofsaid distance;

said step of generating a fourth signal representing a dimensiontransverse to said direction of motion at a plurality of locations alongthe object includes the step of generating a plurality of differentsecond-dimension sets of signals with each set of signals beingproportional to said dimension transverse to said direction of motion atthe location of a different one of said increments of said distancemoved; and

said step of obtainng the second signal includes the steps of addingeach of the second-dimension sets of signals, with the first-dimensionincrement signals and second-dimension sets of signals beingdimensionally adjusted so that when the seconddimension sets of signalsare added, they represent the sum of the products of each increment inthe direction of motion and the second-dimension set of signalscorresponding to that increment, whereby said sum represents the area ofthe object that is scanned.

5. A method according to claim 4 further comprising the steps of:

forming an image of said dimension transverse to said direction ofmotion as said part of said second portion is moved with respect to saidpart of said first portion; and

reducing said image in size;

said step of generating said fourth signal comprising the step ofgenerating a signal that is proportional to the size of said reducedimage.

6. A method according to claim 2 in which the step of generating afourth signal comprises the step of:

transmitting light through an elongated slit extending in the directionof said dimension transverse to said direction of motion, and alignedwith said object to form a line image; and

projecting said image upon a light sensing array.

7. A method according to claim 2 in which the step of generating afourth signal comprises the step of:

scanning the object in a direction transverse to said direction ofmotion with a flying spot to form a modulated beam of light; and

sensing said modulated beam of light with at least one light sensitiveelement.

8. Apparatus for measuring the area of a substantially stationaryobject, comprising:

a portable measuring instrument;

said portable measuring instrument including first and second portionsmovable with respect to each other;

said first portion including a part adapted to be positioned at a fixedlocation with respect to said substantially stationary object, whereby areference location on said object is established;

said second portion including a signal generating means for generatingat least a first signal when said second portion is moved with respectto said part of said first portion while said object is substantiallystationary in such a manner that said first signal is independent of therate of moving said second portion with respect to said part of saidfirst portion and related to a function of the distance between saidpart of said first portion and said second portion and a dimension ofsaid object in a direction transverse to the direction of motion of saidsecond portion with respect to said part; and

calculator means for obtaining a second signal from said first signalrepresenting the area of said object across which said second portionhas moved.

9. Apparatus according to claim 8 in which:

said signal generating means includes first-dimension signal generatingmeans for generating a third signal when said second portion is atdifferent locations with respect to said first portion in such a mannerthat said third signal is independent of the rate of moving said secondportion with respect to said first portion and second-dimension signalgenerating means for generating a fourth signal representing saiddimension of said object in said direction transverse to said directionof motion; and

said calculator means includes means for obtaining a second signalrepresenting the area of said object from said third and fourth signals.

10. Apparatus according to claim 9 in which:

one of said third and fourth signals is a length signal and the other isa width signal;

said first-dimension signal generating means includes means forgenerating one of a different length signal and a different width signalat each of certain predetermined increments of motion;

said second-dimension signal generating means includes means forgenerating the other of a different length signal and a different widthsignal at each of said certain predetermined increments; and

said calculator means includes means for adding the product of the widthand length signals at each of aid increments to provide an integral ofone of said dimensions with respect to the other.

11. Apparatus according to claim 10 in which:

said means for generating one of a different length signal and differentwidth signal includes means for generating one pulse at each dimensionalunit of motion of said second portion with respect to said part of saidfirst portion;

said means for generating the other of a different length signal anddifferent width signal includes means for generating a number of pulsesequal to the dimension transverse to the direction of motion in the samedimensional system as said dimensional unit of motion; and

said calculator means is an accumulator for adding the pulses of saidmeans for generating the other of a different length signal anddifferent width signal.

12. Apparatus according to claim 11 in which:

said first portion includes an elongated member;

said part of said first portion comprises one end of said elongatedmember; and

said first-dimension signal generating means includes at least a portionof said elongated member and means cooperating with said elongatedmember to generate pulses as said elongated member moves within the saidsecond portion.

13. Apparatus according to claim 12 in which said second-dimensionsignal generating means includes:

verse to the direction of motion at said dimensional units in responseto the efiect of said object of said light.

14. Apparatus according to claim 13 in which said means for directinglight comprises a flying spot scanner.

15. Apparatus according to claim 13 in which:

said means for directing light comprises a surface which is opaque to atleast one frequency of light positioned between said source of light andsaid light sensitive means;

said surface having internal walls defining a slit that transmits saidone frequency of light extending in the direction of said dimensiontransverse to said motion;

said slit being sufficiently long to extend beyond the edges of theobject; and

said surface being connected for movement with said second portion.

16. Apparatus according to claim 12 in which said source of lightcomprises light-emitting diodes.

1. A method of measuring the area of a substantially stationary objectwith a portable instrument having at least first and second portionsmovable with respect to each other without moving the object to a newlocation comprising the steps of: bringing the portable measuringinstrument to the location where the stationary object to be measured islocated; establishing a reference location with respect to the object byplacing at least one part of said first portion of the measuringinstrument at a position that is stationary with respect to the object;moving at least one part of the second portion with respect to theobject while the part of the first portion is stationary with respect tothe object and said object remains substantially stationary; sensing thedistance the part of the second portion moves with respect to the partof the first portion and a dimension of the object that is transverse tothe direction of motion of the part of the second portion; generating atleast a first signal related to the distance moved by the part of thesecond portion and the dimension transverse to the direction moved; andobtaining a second signal representing the area of said object from saidfirst signal.
 2. A method according to claim 1 in which: the step ofgenerating said first signal includes the steps of generating a thirdsignal which is independent of the rate of motion of said part of saidsecond portion with respect to said part of said first portion anddependent on the distance said part of said second portion moves withrespect to said part of said first portion, and generating a fourthsignal representing said dimension transverse to the direction moved;and the step of obtaining said second signal includes the step ofobtaining said second signal from said third and fourth signals.
 3. Amethod According to claim 2 in which the step of obtaining said secondsignal representing the area of said object includes the step ofperiodically multiplying increments of said third signal by said fourthsignal to obtain the integral of one of said third and fourth signalswith respect to the other of said third and fourth signals.
 4. A methodaccording to claim 2 in which: said step of generating a third signalwhich is independent of the rate of scanning includes the step ofgenerating a plurality of different first-dimension increment signalseach representing one increment of said distance; said step ofgenerating a fourth signal representing a dimension transverse to saiddirection of motion at a plurality of locations along the objectincludes the step of generating a plurality of differentsecond-dimension sets of signals with each set of signals beingproportional to said dimension transverse to said direction of motion atthe location of a different one of said increments of said distancemoved; and said step of obtaining the second signal includes the stepsof adding each of the second-dimension sets of signals, with thefirst-dimension increment signals and second-dimension sets of signalsbeing dimensionally adjusted so that when the second-dimension sets ofsignals are added, they represent the sum of the products of eachincrement in the direction of motion and the second-dimension set ofsignals corresponding to that increment, whereby said sum represents thearea of the object that is scanned.
 5. A method according to claim 4further comprising the steps of: forming an image of said dimensiontransverse to said direction of motion as said part of said secondportion is moved with respect to said part of said first portion; andreducing said image in size; said step of generating said fourth signalcomprising the step of generating a signal that is proportional to thesize of said reduced image.
 6. A method according to claim 2 in whichthe step of generating a fourth signal comprises the steps of:transmitting light through an elongated slit extending in the directionof said dimension transverse to said direction of motion, and alignedwith said object to form a line image; and projecting said image upon alight sensing array.
 7. A method according to claim 2 in which the stepof generating a fourth signal comprises the steps of: scanning theobject in a direction transverse to said direction of motion with aflying spot to form a modulated beam of light; and sensing saidmodulated beam of light with at least one light sensitive element. 8.Apparatus for measuring the area of a substantially stationary object,comprising: a portable measuring instrument; said portable measuringinstrument including first and second portions movable with respect toeach other; said first portion including a part adapted to be positionedat a fixed location with respect to said substantially stationaryobject, whereby a reference location on said object is established; saidsecond portion including a signal generating means for generating atleast a first signal when said second portion is moved with respect tosaid part of said first portion while said object is substantiallystationary in such a manner that said first signal is independent of therate of moving said second portion with respect to said part of saidfirst portion and related to a function of the distance between saidpart of said first portion and said second portion and a dimension ofsaid object in a direction transverse to the direction of motion of saidsecond portion with respect to said part; and calculator means forobtaining a second signal from said first signal representing the areaof said object across which said second portion has moved.
 9. Apparatusaccording to claim 8 in which: said signal generating means includesfirst-dimension signal generating means for generating a third signalwhen said second Portion is at different locations with respect to saidfirst portion in such a manner that said third signal is independent ofthe rate of moving said second portion with respect to said firstportion and second-dimension signal generating means for generating afourth signal representing said dimension of said object in saiddirection transverse to said direction of motion; and said calculatormeans includes means for obtaining a second signal representing the areaof said object from said third and fourth signals.
 10. Apparatusaccording to claim 9 in which: one of said third and fourth signals is alength signal and the other is a width signal; said first-dimensionsignal generating means includes means for generating one of a differentlength signal and a different width signal at each of certainpredetermined increments of motion; said second-dimension signalgenerating means includes means for generating the other of a differentlength signal and a different width signal at each of said certainpredetermined increments; and said calculator means includes means foradding the product of the width and length signals at each of saidincrements to provide an integral of one of said dimensions with respectto the other.
 11. Apparatus according to claim 10 in which: said meansfor generating one of a different length signal and different widthsignal includes means for generating one pulse at each dimensional unitof motion of said second portion with respect to said part of said firstportion; said means for generating the other of a different lengthsignal and different width signal includes means for generating a numberof pulses equal to the dimension transverse to the direction of motionin the same dimensional system as said dimensional unit of motion; andsaid calculator means is an accumulator for adding the pulses from saidmeans for generating the other of a different length signal anddifferent width signal.
 12. Apparatus according to claim 11 in which:said first portion includes an elongated member; said part of said firstportion comprises one end of said elongated member; and saidfirst-dimension signal generating means includes at least a portion ofsaid elongated member and means cooperating with said elongated memberto generate pulses as said elongated member moves within the said secondportion.
 13. Apparatus according to claim 12 in which saidsecond-dimension signal generating means includes: a source of light;means for directing light from said source of light against said object;and light sensitive means for generating a number of electrical pulsesproportional to the dimension transverse to the direction of motion atsaid dimensional units in response to the effect of said object of saidlight.
 14. Apparatus according to claim 13 in which said means fordirecting light comprises a flying spot scanner.
 15. Apparatus accordingto claim 13 in which: said means for directing light comprises a surfacewhich is opaque to at least one frequency of light positioned betweensaid source of light and said light sensitive means; said surface havinginternal walls defining a slit that transmits said one frequency oflight extending in the direction of said dimension transverse to saidmotion; said slit being sufficiently long to extend beyond the edges ofthe object; and said surface being connected for movement with saidsecond portion.
 16. Apparatus according to claim 12 in which said sourceof light comprises light-emitting diodes.